[Driver] Forward pass plugin arguments to gold

[ddcc]

Summary

Support forwarding -fplugin and -fpass-plugin arguments for loading pass plugins

Depends on: D77704

[ddcc]

Originally, I tried forwarding the -Xclang -load arguments, but couldn't access the options::OPT_plugin arguments from the argument list. I'm not familiar with tablegen and argument processing, there was some issue with the group not being available causing the arguments to be skipped when filtering the argument list, so I ended up reusing the OPT_fplugin and OPT_fpass_plugin arguments instead. As far as I can tell, OPT_fplugin seems to work for both Clang and LLVM plugins, but I haven't used the former.

clang/lib/Driver/ToolChains/CommonArgs.cpp

if (CSPGOGenerateArg) {
     } else
       CmdArgs.push_back(
           Args.MakeArgString("-plugin-opt=cs-profile-path=default_%m.profraw"));
   } else if (ProfileUseArg) {
     SmallString<128> Path(
         ProfileUseArg->getNumValues() == 0 ? "" : ProfileUseArg->getValue());
     if (Path.empty() || llvm::sys::fs::is_directory(Path))
       llvm::sys::path::append(Path, "default.profdata");
-    CmdArgs.push_back(Args.MakeArgString(Twine("-plugin-opt=cs-profile-path=") +
-                                         Path));
+    CmdArgs.push_back(
+        Args.MakeArgString(Twine("-plugin-opt=cs-profile-path=") + Path));
   }
 
+  // Forward arguments for loading plugins (old/new PM)
+  for (const Arg *A : Args.filtered(options::OPT_fplugin_EQ))
+    CmdArgs.push_back(
+        Args.MakeArgString(Twine("-plugin-opt=load=") + A->getValue()));
+  for (const Arg *A : Args.filtered(options::OPT_fpass_plugin_EQ))
+    CmdArgs.push_back(Args.MakeArgString(
+        Twine("-plugin-opt=load-pass-plugin=") + A->getValue()));
+
   // Need this flag to turn on new pass manager via Gold plugin.
   if (Args.hasFlag(options::OPT_fexperimental_new_pass_manager,
                    options::OPT_fno_experimental_new_pass_manager,
                    /* Default */ ENABLE_EXPERIMENTAL_NEW_PASS_MANAGER)) {
     CmdArgs.push_back("-plugin-opt=new-pass-manager");
   }
 
   // Setup statistics file output.